<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>数据类型</title>
		<script>
			// 基本数据类型：数字、字符串、布尔类型
			// JS中的数组可以存放任意类型的数据
			let arr = ['a', 'b', 3, true, []]
			// JS中对象
			let obj = {name: '林俊杰', age: 21}
			// 装人对象的数组
			let userList = [
				{
					name: "林俊杰",
					age: 21,
					grade: "20224128",
					sex: 0,
					hobby: undefined
				},
				{
					name: "邓紫棋",
					age: 21,
					grade: "20224129",
					sex: 1,
					hobby: null
				},
				{
					name: "刘德华",
					age: 20,
					grade: "20224128",
					sex: 0,
					hobby: ["演唱会", "拍电影"]
				},
				{
					name: "Beyond",
					age: 26,
					grade: "20224128",
					sex: 0,
					hobby: []
				},
				{
					name: "杨幂",
					age: 20,
					grade: "20224129",
					sex: 1,
					hobby: ["追剧"]
				},
				{
					name: "周杰伦",
					age: 21,
					grade: "20224128",
					sex: 0,
					hobby: ["唱歌", "mojito"]
				},
				{
					name: "kunkun",
					age: 19,
					grade: "20224129",
					sex: 0,
					hobby: ["唱", "跳", "rap", "篮球"]
				}
			]
			
			let c
			console.log(c) // undefined，表示变量未赋值
		</script>
	</head>
	<body>
		
	</body>
</html>